springsecurity 之 登录用户数据的获取
springsecurity中，用户登录信息本质是保存到HttpSession中，springsecurity进行封装 获取登录数据有两种思路：
- 从SecurityContextHolder中获取
- 从当前请求对象中获取
从SecurityContextHolder中获取
@RestController
public class HelloController {
@GetMapping("/hello")
public void hello() {
Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
System.out.println("authentication.getClass() = " + authentication.getClass());
}
}SecurityContextHolder存放的是SecurityContext ，SecurityContextHolder中定义三种不同的数据存储策略，采用了策略模式
- MODE_THREADLOCAL ：将SecurityContext放在ThreadLocal中，开启子线程，子线程获取不到用户数据。
- MODE_INHERITABLETHREADLOCAL：多线程环境，子线程也能获取到用户数据。
- MODE_GLOBAL：数据保存到一个静态变量中，web开发中很少使用。
SecurityContextHolderStrategy接口用来规范存储策略中的方法
public interface SecurityContextHolderStrategy {
void clearContext();
SecurityContext getContext();
void setContext(SecurityContext var1);
SecurityContext createEmptyContext();
}有三个实现类 对应三个不同的存储策略
ThreadLocalSecurityContextHolderStrategy
//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by FernFlower decompiler)
//
package org.springframework.security.core.context;
import org.springframework.util.Assert;
final class ThreadLocalSecurityContextHolderStrategy implements SecurityContextHolderStrategy {
private static final ThreadLocal<SecurityContext> contextHolder = new ThreadLocal();
ThreadLocalSecurityContextHolderStrategy() {
}
public void clearContext() {
contextHolder.remove();
}
public SecurityContext getContext() {
SecurityContext ctx = (SecurityContext)contextHolder.get();
if (ctx == null) {
ctx = this.createEmptyContext();
contextHolder.set(ctx);
}
return ctx;
}
public void setContext(SecurityContext context) {
Assert.notNull(context, "Only non-null SecurityContext instances are permitted");
contextHolder.set(context);
}
public SecurityContext createEmptyContext() {
return new SecurityContextImpl();
}
}存储载体是ThreadLocal 针对SecurityContext的操作都是在ThreadLocal中进行操作。SecurityContext只是个接口，只有一个实现类是SecurityContextImpl
InheritableThreadLocalSecurityContextHolderStrategy
//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by FernFlower decompiler)
//
package org.springframework.security.core.context;
import org.springframework.util.Assert;
final class InheritableThreadLocalSecurityContextHolderStrategy implements SecurityContextHolderStrategy {
private static final ThreadLocal<SecurityContext> contextHolder = new InheritableThreadLocal();
InheritableThreadLocalSecurityContextHolderStrategy() {
}
public void clearContext() {
contextHolder.remove();
}
public SecurityContext getContext() {
SecurityContext ctx = (SecurityContext)contextHolder.get();
if (ctx == null) {
ctx = this.createEmptyContext();
contextHolder.set(ctx);
}
return ctx;
}
public void setContext(SecurityContext context) {
Assert.notNull(context, "Only non-null SecurityContext instances are permitted");
contextHolder.set(context);
}
public SecurityContext createEmptyContext() {
return new SecurityContextImpl();
}
}存储载体为InheritableThreadLocal ，InheritableThreadLocal继承ThreadLocal，多了一个特性，就是在子线程创建的时间，会自动将父线程的数据复制到子线程中。实现了子线程中能够获取登录数据的功能。
GlobalSecurityContextHolderStrategy
//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by FernFlower decompiler)
//
package org.springframework.security.core.context;
import org.springframework.util.Assert;
final class GlobalSecurityContextHolderStrategy implements SecurityContextHolderStrategy {
private static SecurityContext contextHolder;
GlobalSecurityContextHolderStrategy() {
}
public void clearContext() {
contextHolder = null;
}
public SecurityContext getContext() {
if (contextHolder == null) {
contextHolder = new SecurityContextImpl();
}
return contextHolder;
}
public void setContext(SecurityContext context) {
Assert.notNull(context, "Only non-null SecurityContext instances are permitted");
contextHolder = context;
}
public SecurityContext createEmptyContext() {
return new SecurityContextImpl();
}
}存储载体是一个静态变量，也可以在多线程环境下使用，但用的较少。
SecurityContextHolder源码
//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by FernFlower decompiler)
//
package org.springframework.security.core.context;
import java.lang.reflect.Constructor;
import org.springframework.util.ReflectionUtils;
import org.springframework.util.StringUtils;
public class SecurityContextHolder {
public static final String MODE_THREADLOCAL = "MODE_THREADLOCAL";
public static final String MODE_INHERITABLETHREADLOCAL = "MODE_INHERITABLETHREADLOCAL";
public static final String MODE_GLOBAL = "MODE_GLOBAL";
public static final String SYSTEM_PROPERTY = "spring.security.strategy";
private static String strategyName = System.getProperty("spring.security.strategy");
private static SecurityContextHolderStrategy strategy;
private static int initializeCount = 0;
public SecurityContextHolder() {
}
public static void clearContext() {
strategy.clearContext();
}
public static SecurityContext getContext() {
return strategy.getContext();
}
public static int getInitializeCount() {
return initializeCount;
}
private static void initialize() {
if (!StringUtils.hasText(strategyName)) {
strategyName = "MODE_THREADLOCAL";
}
if (strategyName.equals("MODE_THREADLOCAL")) {
strategy = new ThreadLocalSecurityContextHolderStrategy();
} else if (strategyName.equals("MODE_INHERITABLETHREADLOCAL")) {
strategy = new InheritableThreadLocalSecurityContextHolderStrategy();
} else if (strategyName.equals("MODE_GLOBAL")) {
strategy = new GlobalSecurityContextHolderStrategy();
} else {
try {
Class<?> clazz = Class.forName(strategyName);
Constructor<?> customStrategy = clazz.getConstructor();
strategy = (SecurityContextHolderStrategy)customStrategy.newInstance();
} catch (Exception var2) {
ReflectionUtils.handleReflectionException(var2);
}
}
++initializeCount;
}
public static void setContext(SecurityContext context) {
strategy.setContext(context);
}
public static void setStrategyName(String strategyName) {
SecurityContextHolder.strategyName = strategyName;
initialize();
}
public static SecurityContextHolderStrategy getContextHolderStrategy() {
return strategy;
}
public static SecurityContext createEmptyContext() {
return strategy.createEmptyContext();
}
public String toString() {
return "SecurityContextHolder[strategy='" + strategyName + "'; initializeCount=" + initializeCount + "]";
}
static {
initialize();
}
}SecurityContextHolder 定义三个静态常量描述三种不同存储策略，在静态代码块中初始化，根据不同的strategyName初始化不同的存储策略，可以调用配置系统变量或者调用setStrategyName改变策略。
在默认情况下，从子线程中获取登录数据是获取不到的，因为默认是MODE_THREADLOCAL策略。
存储策略在System.getProperty("spring.security.strategy");加载，可以配置系统变量来修改策略。
在VM option参数添加
-Dspring.security.strategy=MODE_INHERITABLETHREADLOCAL
SpringContextHolder默认将用户信息存储在ThreadLocal中，在SpringBoot中不同的请求使用不同的线程处理，是怎么获取到用户的信息的呢？ 下篇文章揭晓，有懂的可以在评论区留言。
